The chief purpose of such new editions is to bring the text up to date. This I have tried to do. The danger with such endeavours is that the book becomes corpulent. This I have tried to avoid. In so doing I am evermore conscious of how much material has had to be omitted. As before the references (ca. 770 of them) which are cited are intended in part to provide the reader with access to material that has been omitted. I am deeply grateful to Mrs Marjorie Romanowicz for preparing the typed manuscript for this edition with customary accuracy and efficiency, to my wife Margaret for checking the references, and to research students Karl Cable, Lucy Hyatt, Mashupye Kgaphola and Andrew Knaggs for helping with the checking of the manuscript. Richard Herbert April 1988 Preface to the first edition This is a book about experiments and results of experiments. The results described are the fruit of thirty years' labour in the field of secondary metabolism. Secondary metabolism, more than any other part of the chemistry of life, has been the special preserve of organic chemists. Investigation of secondary metabolism began with curiosity about the structures of compounds isolated from natural sources, i.e. secondary metabolites. Coeval with structure determination there has been a curiosity about the origins and mechanism of formation of secondary metabolites (or natural products as they have been called). It is the experimental outcome of this curiosity that is described here.